Container filling and sealing machines



Feb. 21, 1961 R. SCHMIDT 2,972,216

CONTAINER FILLING AND SEALING MACHINES Filed July 28, 1958 9Sheets-Sheet 1 inventor Rudolph chmidt By his Attorney W Oil/(1p Feb.21, 1961 R. SCHMIDT 2,972,216

CONTAINER FILLING AND SEALING MACHINES Filed July 28, 1958 sSheets-Sheet 2 Feb. 21, 1961 R. SCHMIDT 2,972,216

, CONTAINER FILLING AND SEALING MACHINES Filed July 28. 1958 r 9Sheets-Sheet s Feb. 21, 1961 R. SCHMIDT CONTAINER FILLING AND SEALINGMACHINES 9 Sheets-Sheet 4 Filed July 28. 1958 Feb. 21, 1961 R. SCHMIDTCONTAINER FILLING AND SEALING MACHINES Q a WWHEHHHHHUHHQ E w 7 w M H m Q6 a i= fizz:

Filed July 28, 1958 Filed July 28. 1958 9 Sheets-Sheet 6 Feb. 21, 1961R. SCHMIDT 2,972,216

CONTAINER FILLING AND SEALING MACHINES Filed July 2a, 1958 9Sheets-Sheet 7 F 1! V176 T Feb. 21, 1961 R. SCHMIDT 2,972,216

CONTAINER FILLING AND SEALING MACHINES Filed July 28,1958 9 Sheets-Sheeta Feb. 21, 1961 R. SCHMIDT 2,972,216

CONTAINER FILLING AND SEALING MACHINES Filed July 28. 1958 9Sheets-Sheet s Fql l L\ Q [in 246 1 Y1 250 l \j I W :5 g x o 24; m"\

United States Patent CONTAINER FILLING AND SEALING MACWES RudolphSchmidt, Scotch Plains, N.J., assignor to United Shoe MachineryCorporation, Flemington, N.J., a corporation of New Jersey Filed July28, 1958, Ser. No. 751,519

8 Claims. (Cl. 53-281) This invention relates to packaging and moreparticularly to machinery for filling and sealing containers. The use ofdisposable containers holding small quantities of products which are tobe consumed Without the containers subsequently being rescaled presentsa definite advantage in convenience of handling and distribution whenthe protection afforded by the containers to their contents permitslengthy storage before use. For example, food products, such as jams,syrups, condiments, etc, packaged in quantities representing singleservings or portions, in receptacles known as unit containers, arebecoming increasingly more popular in restaurants, railroads, airlines,and the like. Since these containers most often are distributed directlyto their ultimate consumers for immediate use they must be easily openedwithout the aid of tools, such as a conventional can opener.

For the most part, unit containers have been made of inexpensiveflexible plastic material. However, a major disadvantage of a containermade of this type of material is that it is susceptible to thepenetration of air, and

accordingly its conents, if perishable, may spoil in a relatively shorttime. To overcome this and therefore provide a longer shelf life, unitcontainers are being made of lightweight metals, such as aluminum,which, when hermetically sealed by plastic fusion with a cover of likematerial, afiord protection to their contents for a considerably longertime and furthermore can be opened without the use of tools. Since theadvantage of the system of unit portion distribution is economicallypredicated upon high quantity production, it is mandatory that reliable,relatively high speed machinery, both automatic and semiautomatic, beemployed in the production and handling of unit containers. It is tothis end that this invention is directed.

One of the objects of the present invention is to provide a machine forfilling unit containers and sealing them with an easily removable coverthereby to provide an airtight package which may be opened without theaid of tools.

Another object of this invention is to provide an easily cleaned unitcontainer filling and sealing machine which is particularly adapted tothe handling of food products.

Another object of this invention is to provide a unit container fillingand sealing machine in which the instrumentalities which come in contactwith the container are completely separated from the drivinginstrumentalities.

Still another object of this invention is the provision of a unitcontainer filling and sealing machine which has various operatinginstrumentalities all of which are 2,972,216 Patented Feb. 21, 1961operated from self-contained hydraulic and pneumatic systems requiringno outside supply of fluid or gas.

A typical unit container is a shallow, substantially cylindrical,cup-like receptacle generally of aluminum, having a flange extendingradially around the open end. The interior of the cup and the uppersurface of the flange are coated with a thermoplastic material, such asvinyl. An aluminum cap or cover, which may be provided with a label, ishermetically sealed to the upper end of each indexing motion.

surface of the flange through fusing of the vinyl coatings on thecontacting surfaces of the cover and of the flange.

In accordance with the above objects and as a feature of this inventionthere is provided a machine having a turret with a plurality of cavitiesformed to receive flanged unit containers of the type described above.The turret, which may be loaded automatically or by hand, indexes thecontainers to a piston-type filling machine which deposits apredetermined quantity of material in each of the containers. From thefilling station, the container is indexed to mechanism which positions acover on the flange of the filled container. Next, the covered containeris sealed by mechanism which causes the contacting vinyl coated surfacesof the cover and the flange to be fused thereby producing an airtightseal. The final step is the removal of the sealed container from theturret by mechanism which elevates the containers from the cavities anddisplaces them onto a collecting chute or trough. The turret is indexedby a Geneva drive mechanism which is particularly designed so as not tospillthe contents of the containers by the provision of means forreducing the acceleration and deceleration at the beginning and Each ofthe operating instrumentalities or Work stations including the filler,cover positioner, sealer and ejector, etc., are operated by individualhydraulic cylinders, the cylinders in turn being operated by mastercylinders of the type commonly used to operate automobile brakes. All ofthe master cylinders are cam operated and are positioned within ahousing or compartment separated from the operating instrumentalities.The cover positioning member is operated in part pneumatically, but doesnot require an outside source of vacuum or compressed air, both beingprovided by a single unit contained within the above-mentionedcompartment and likewise operated by cam mechanism within thecompartment. All of the operating instrumentalities are arranged to bereadily cleaned, and constructed of non-corrosive material andpositioned so that any spilled material can be readily removed, forexample, by the application of pressurized steam, without disassemblingthe machine or its driving mechanism.

The above and other features of the invention including various noveldetails of construction and combinations of parts will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims.

Fig. l is a perspective view of a container filling and sealing machineembodying the invention;

Fig. 2 is a plan view of the machine shown in Fig. 1;

Fig. '3 is a right side elevation, partly in section, of the machineshown in Fig. 1;

'Fig. 4 is a plan view, partly in section, of portions of the fillingapparatus;

Fig. is a rear elevation of the filling apparatus shown in Fig. 4;

Fig. 6 is a sectional view taken on the line Vl-VI of Fig. 4;

Fig. 7 is a plan view of a portion of the cap positioning mechanism;

Fig. 8 is a side elevation of the cap positioning mechanism shown inFig. 7;

Fig. 9 is a rear elevation of the cap positioning mecha nism shown inFigs. 7 and 8;. a

Fig. 10 is a sectional view of the cap sealing mechanism taken along'theline X-X of Fig. 2;-

Figs, 11, 12 and 13 are detail views of the container ejectingmechanism; V a

Fig. His 2. plan view of the main portions of the driving mechanism; Y

a Fig. 15 is a plan view with parts broken away of the intermittentdrive mechanism for rotating the turret; and I Fig. 16 is a section viewof portions of the drive mechanism on the line XVIXVI of Fig. 15.

Referring to Figs. 2 and 3, the illustrative machine comprises a mainframe 2 having a lower enclosed compartment 4 in which are located allof the driving instrumentalities. The compartment 4 is completely closedin order that the driving instrumentalities will be protected when theoperating portions of the machine are cleaned, as for example, bypressurized steam. A table 6 of non-corrosive material such as stainlesssteel, separates the various operating instrumentalities, from thedriving instrumentalities within the compartment 4.

For supporting the individual unit containers and transporting them tothe various work stations comprising the'operating instrumentalities' isa turret 8. Formed in the turret are a plurality of container receivingcavities 10, each of which is lined with an annular insulatingdrivemechanism 22 which will be described in more detail hereinafter.

Empty containers are moved from a loading table 23 by an operator andpositioned in the cavities 10 in the a turret 8. The containers areindexed intermittently in a clockwise direction as viewed in Figs. 1 and2 to a filling station or'filler 24 which deposits a predeterminedquantity of material in each container. The illustrated machine isdesigned to fill the containers with a liquid material from'a pipe 25which, as seen in Fig. 3, is constructed with sharp angular bends toreduce the possibility of dripping to a minimum. Any overflow ofmaterial passes into a collecting cup 26 (Fig. 3)'in the table 6 andthence to a removable tray 28 within the compartment 4. I

The filler 24, best seen in Figs. 4, 5 and 6, comprises a conicalreservoir 30 mounted on a main body or cylinder housing 32. .Rotatablewithin the body 32 is a valve 34. having a first passageway 36 extendingdiametrically through the valve and a second passageway 38 extendingradially intersecting the passageway 36 at an angle of 90. 'Alongitudinally extending cylinder 40. communicates' with the valve 34and slidable within the cylinder is a piston 42 fromwhich extends apiston rod 44. The

valve 34 is rotated between a first or intake position where in thepassageway 36 isiin alignment with a vertical V the following manner.

passageway 46 communicating'with the reservoir 30. In 7 this positionthe passageway'38-is in communicationwith way 38 is blocked and thepassageway 36 communicates with a horizontal passageway 43 leading tothe filler pipe 25. Adjustably connected to the piston rod 44 by athreaded link 5t and adjusting nuts 51 is a fluid motor or hydrauliccylinder 52, of conventional design, such as that known as an AiroyalCylinder, H-series. Connected to the rotary valve 34 by a crank 54 andan adjusting rod 56 is another fluid motor 58 of like design. The motors52 and 58 are single acting, each having a return stroke controlled byan appropriatespring (not shown).

Rotation of the valve 34 and the reciprocation of the piston 42 takeplace in synchronisrn under the control of their respective fluidmotors, whereby when the valve 34 is in its intake position the piston42 is moved to the right thereby drawing fluid from the reservoir intothe cylinder 49 and when the valve 34 is moved to the dischargepositionyas seen in Fig. 6, the piston 42 is moved toward the leftthereby forcing the fluid from the cylinder 40 into the discharge pipe25. The stroke of the piston 42 is determined by rotation of the link 50and the adjusting nuts 51 whereby the quantity of fluid deposited ineach container may be accurately controlled.

From the filling station 24 the containers are moved by the turret tothe cap or cover positioning mechanism 53, best seen in detail in Figs.7 through 9. A stack of covers 62 are held in a magazine'64 comprising aplurality of spaced rods 66 mounted in an apertured plate 68. Fitted inthe bottom of the plate 68 are a plurality of inwardly extending fingers79 to keep the covers from falling out of the magazine but ofsufficiently smallsize as not to impede the removal 'of covers from themagazine. The plate 68 i's secured between arms 72, the opposite ends ofwhich are pivoted on fulcrum pins 74 fitted in a bracket 76 which inturn is secured byscrews 78 to a main'bodyrportion 80 of the cappositioning mechanism. Mounted on a cross plate 82 bridging the arms 72is a fluid motor 84. A piston rod 86 projects from the fluid motor 84through a bore 87 in the plate 82 and adjustably mounts on its lower enda pivot bearing 88. The bearing 88 engages and upper horizontal surface90 of the main body portion 80 of the positioning mechanism. Themagazine, and consequently the covers contained therein, are oscillatedabout the fulcrum 74 through an arc of an acute angle when thepivotbearing .88 alternately is extended from and retracted toward the main'body of the fluid motor 84.

The bottommost cover is picked from the magazine 64 by a vacuum picker94; Fitted in the lower flanged end of the picker is a disk 96 ofrubber, or the like, having a plurality of holes 98 communicating with'a passageway 100 in the picker 94. The picker is pinned to the end of ahorizontal shaft 102 which is journaled in bearings 104,

106 in the member 8! Extending axially through the' in a guideway by afiuid motor 116; The motor is mounted on a bracket 113 attached to the,member 89 and is adjustably connected to the rack 114 by an adjustablebifurcated link 1253. a i

' The cover picking and positioning means operates in the fluid motor 84pivoting the arms 72 upwardly about the fulcrum' 74. Simultaneouslytherewith, the fluid motor 116, through the rack and pinion" 114 and.112, rotates the picker 94 from the normal or Fig. '8 position Iwherein the picker rests against an adjustable stop 122 in disk 9;6faces upwardly and is positioned directlybelow themagazine 64.; Themagazine is then permitted to The magazine 64 is elevated by descendupon the picker disk 96. The passageways 98 are supplied with negativepressure or vacuumvia the line 110 and the passageways 109 and 108. Themagazine is again elevated slightly whereby the lowermost cover isremoved by the picker which then is rotated again into the normal orFig. 8 position directly above and facing the filled container in theturret 8. The vacuum is then turned ofl and replaced by a slight jet'ofair forcibly'to eject the cover from engagement with the disk 96 and toposition it in engagement with the container flange.

After the cover is placed on top of the container, the turret is indexedto locate the container and its cover C directly beneath a heat sealingelement 129, seen best in Fig. 10. This element comprises a hollowpressure applying head 139 which has secured to its lower end aninverted annular recessed disk 132. The disk is engageable with thecover of the container in a ring directly above the flange. Anannular'heater element 134 is positioned within the head 139 and isconnected electrically in series with a thermostat 136, electrical powerbeing supplied thereto through wires 138 from any appropriate source(not shown). Vertical reciprocating motion is supplied to the pressureapplying head by a fluid motor 140 which is connected to the head by apiston rod 142, a boss 144 and a ceramic insulator 146, thelatter beingsecured to the head 13%) by screws 148 (only one of which is shown). Thefluid motor 140 is mounted on a bracket 15% secured to the top of acylinder 152. The heater element conductor wires 133 and varioushydraulic fluid lines while not shown in the drawings pass through theinterior of the cylinder 152 gaining entrance thereto throughappropriate openings 154 and 156 and thence into the compartment 4through an opening 153 in the table 6. After the container has beenpositioned beneath the pressure applying head 130, the head is forceddownwardly, the heated annular disk 132 forcing the cover against theflange of the container whereupon the vinyl to vinyl surfaces fuse,forming a hermetic seal between the cover and the flange. Added rigidityis afforded the turret 8 during this process by a support 160 secured tothe table 6 beneath the head 133. 7

When the cap has been sealed to the container, the head 130 is retractedupwardly and the turret is indexed to the next station where the filledand sealed-container is removed from the turret. An ejector 169, bestseen in Fig. ll, comprises a substantially cylindrical pusher 17!!secured to an arm 172 which is clamped to a piston 174 projectingupwardly through the table 6 and a rod 1'75. A fluid motor 176 clampedto the undersurf'ace of the table 6 moves the rod 1'75. The piston 174slides within a sleeve 177 in order to prevent dirt and/ or moisturefrom descending into the compartment '4 with the arm 172 projecting froma slot 178 formed in the sleeve. Vfhen the turret is indexed to aposition wherein the container is directly above the pusher 170, thefluid motor 176 raises the pusher 170 which ejects the container fromthe turret. After being ejected, the container is displaced onto adownwardly extending chute by a sweeper arm 152. The arm is secured tothe upper end of a sha t 1.84 journaled within a protective tube 186.Oscillating motion is imparted to the shaft by a fluid motor 138 mountedbelow the table 6 and connected by a bifurcated link 1% to an arm 192which is pinned to the lower end of the shaft 134. Return motion of thesweeper arm 182 is eflected by a tension spring 194. Movement of the armis limited by an adjustable stop member 1% (Fig. 2).

All of the operating instrumentalities including the filler, the coverpositioning mechanism, the sealer and the removing mechanism, etc, areoperated from driving mechanism within the compartment 4. An electricmotor 2% (Fig. 14) through a speed reducer 232 and gears 294, 2 56rotates a main drive shaft 268. The shaft is journaled in pillow blocks21%), 212. A bank of cams A, B, C, D, E, F and G are secured to theshaft 208.

Each cam supplies driving motion to-a corresponding hydraulic mastercylinder 'a, b, c, d, e, f and g through similar cam follower mechanism.Only one cam G, and its follower mechanism, will be described. Referringto Fig. 3, the cam is split and clamped to the shaft 208 by screws (notshown) to permit it to be rotated in order 'to adjust timing. A camfollower 216, engageable with the cam, is pivoted on an arm 218fulcrumed in a bracket 220 on the base of the machine. The arm 218 ispivotally connected by a bifurcated link 222 to an extending piston rod224 of the master cylinder g. In like manner each of the other cams areconnected to their master cylinders. In turn each of the mastercylinders is connected to one of the fluid motors for operating: thefiller, the'cap positioner, the pressure applying head, the ejector andthe sweeper arm, etc. Each of the fluid motors is of the single actingtype similar to the hydraulic brake cylinder of an automobile andaccordingly requires a spring for its return movement. In mostinstances, the springs are not shown in the drawings.

The vacuum and the pressure for the cover picker 94 is obtained from adouble acting air cylinder 226 (Fig. 3) one end of which is pivotallysecured to the machine frame. Projecting from the cylinder 226 is apiston rod 228 which is pivotally connected to an arm 230 which isreciprocated about a fulcrum 232 by a cam 234 (Fig.

14) engageable with a cam follower 236 pivoted on the arm 230. The cam234 is, as are all the other cams, mounted on the main drive shaft 2&3.Since the air cylinder 226 is double acting, movement of the piston rod228 in one direction produces a vacuum and, in the opposite direction, aflow of air through the line which leads to the picker 94'.

The indexing motion of the turret is derived from the above-mentionedintermittent drive mechanism 22. The shaft 20 to which the turret 3 issecured is journaled in bearings 240, 242 (Fig. 16) and has keyed to itslower end a gear 244. Meshing with the gear 244 and secured to a shaft246 is a pinion 248. A Geneva or star wheel 250 is secured to the pinion248 and receives its power from a conventional Geneva driver comprisinga roll 252 arranged to enter slots 253 in the star wheel. The roll ispivoted on the end of a driver arm 254 which in turn is secured to aninput shaft 256. The shaft 256 is driven through a pair of beveled gears258, 260, the latter being secured to a horizontally extending shaft 262journaled in brackets 264, 266.

In order to avoid spilling the contents of the containers at thebeginning and end of each increment of indexing motion where,respectively, the acceleration and deceleration are the greatest, andwithout slowing down the over-all cyclic time of the turret, the motionof the Geneva driver shaft 256 is modified. This shaft is driven in suchmanner that its angular velocity is sinusoidal with the lowest point ofvelocity occuring each time the Geneva driver roll 252 has fullypenetrated a slot 253 in the Geneva star wheel 251 and is about to beginto be withdrawn. Accordingly, the driver roll 252 is decelerating whenit enters the slot and is accelerating when it leaves the slot. This, ofcourse, being opposite to the normal starting acceleration and stoppingdeceleration of a Geneva star wheel, tends partially to reduce theseundesirableconditions resulting in an elimination of spilling.

Sinusoidal angular velocity is imparted to the horizontal shaft 262 and,consequently to the Geneva driver, by an endless chain 276 which passesaround a concentric sprocket wheel 272 (Fig. 3). The chain is drivenfrom an eccentric sprocket wheel 274 mounted on the cam shaft 208 andhaving teeth equal in number to those or the concentric sprocket wheel272. An idler sprocket wheel 276 journaled in a spring-biased arm, 278like wise engages the chain 276.; The cam shaft 208 and, consequentlythe eccentric sprocket 274, are driven at constant angular velocity.However, intermittent -01 semis Sinusoidal linear velocity is impartedto the chain ,270 because of the different peripheral velocities of theteeth on the eccentric sprocket 274 engaging the chain. The sinusoidallinear velocity of the chain is translated directly into sinusoidalangular Velocity of the shaft 262 since the sprocket wheel 272 isconcentric with the shaft. Slack in the chain 270 is taken .up by thespring-biased idler sprocket wheel 276. a Q

c Having thus described my invention, what I claim as new and desiretosecure by Letters Patent of the United Statesis;

1. In a machine for filling'and sealing containers, a turret having aplurality of cavities formed to receive containers, means for filling acontainer, means for positioning a cover on the container comprising apneumatically operated picker having a cover engaging surface, amagazine for holding a stack of covers above said picker, means forrotating the picker about a first horizontal axis from a position wherethe engagings'urface faces the bottommost cover in the magazine to aposition Where it faces toward a container in the turret, means forpivoting the magazine about a second horizontal axis normal to saidfirst axis towardand away from the picker, means for correlating themovement of the picker and the magazine whereby the magazine movestoward the picker when the picker faces toward the bot-' jfilling acontainer, means for positioning a cover on the container, means forforming a hermetic seal, between the cover. and the container and meansfor removing containers from the turret after they have been filled andsealed, means for driving each of said operating elements comprising afluid motor associated therewith, a master cylinderhydraulically'connected to each of said fluid motors, a cam shaft, and aplurality of cams on said shaft, reach cam being associated with onemaster cylinder for imparting an operating stroke thereto, said drivin}; means being contained within a compartment separate from saidoperating instrumentalities.

3. In a machine 'for filling and sealing containers, a plurality of workstations comprising means for filling a container, 'means forpositioning a cover on the container and means for sealing the cover tothe container, a turret for conveying containers to said work stations,means for indexing said turret intermittently. comprising aiGeneva drivemechanism, and means for delivering sinusoidal input to said Genevamechanism to reduce acceleration and deceleration at the beginningand'end of each indexing movement thereby to eliminate spilling thecontents of the filled containers.

4."-In a machine for filling and sealing containers, 'a plurality .ofwork stations comprising means for filling a container, means forpositioning a cover'on the container and means for sealing the cover tothe container, a turret'for conveying containers'to said work stations,

means for indexing said turret intermittently comprising 4 a Genevadrive mechanism, means for delivering sinusoidal input to said Genevamechanism to reduce accel oration and deceleration at the beginning andend of connecting said sprockets, and means for taking up slack insaidchain.

"SJIna machine for filling' 'and sealing containers, 'a

turret having a plurality of cavities formed to receive containers,means for filling a container, means for positioning a cover on thecontainer comprising a pneumatically operated picker having a coverengaging surface, a magazine for holding a stack. of covers above saidpicker, means .for rotating the picker from a position Where theengaging surface faces the bottommost cover in the magazine to aposition where it faces toward a container in the turret, means formoving the magazine toward and away fromthe picker to present thebottommost cover to the picker and fluid pressure means assocontainers,operating elements comprising means for fill-V ing a container, meansfor positioning a cover on the container, means for forming a hermeticseal between the cover and'the container and means for removingcontainers from the turret after they have been filled and sealed, meansfor driving each of said operating elementscomprising a fluid motorassociated therewith, a master cylinder hydraulically connected to eachof said fluid motors; a cam shaft, and a plurality of cams on saidshaft, each cam being associated with one master cylinder for impartingan operating stroke thereto, said driving means ,being contained withina compartment separate from said operating instrumentalities, means forindexing said turret intermittently comprising a Geneva drive mechanism,and means for delivering sinusoidal input to said Geneva mechanism toreduce acceleration and deceleration at the beginning and end of eachindexing movement thereby to eliminate spilling the contents of thefilled containers.

7. In a container filling and capping machine, a cover magazine, meansforsupporting a filled container to be capped directly below saidmagazine, means. for transferring the bottomrnost cover in said magazineonto the container, said means comprising a cover picking andpositioning means having a cover engaging member, means mounting saidcover picking and positioning means for rotation about a fixedhorizontal axis, means for moving said cover picking and positioningmeans about said axis between a delivery position in which the coverengaging member is'located directly over a container on the supportingmeans and a receiving position spaced therefrom, and means for movingthe magazine substantially vertically toward and away fro-m the coverengaging member in" timed relation to the movement of the cover pickingand positioning means whereby the magazine is moved out of the path ofthe'cover pickingrand positioning means to permit movement of said meansinto and out of the receiving position and is moved toward the coverpicking andpositioning means when said means is in the receivingposition.

8. In a container filling and capping machine, a cover magazine, meansfor supporting a filled container to be capped'directly below saidmagazine, means for transferring the bottomrnost cover in said magazineonto the container, said means comprising a cover picking andpositioning means having a cover engaging member,

means mounting said cover picking and positioning means for rotationabout a fixed horizontal axis, means for moving said cover picking andpositioning means about said axis between a delivery position in whichthe cover engaging-member is located directly over a con tainer' on thesupporting means anda receiving position spaced 180 therefrom, means formoving the magazine substantially vertically toward and away from thecover engaging member in timed relation to the movement of the coverpicking and positioning means whereby the magazine is moved out of thepath of the cover picking and positioning means to permit movement ofsaid means into and out of the receiving position and is moved towardthe cover picking and positioning means when said means is in thereceiving position, and means operative in timed relation to themovement of the cover picking and positioning means for causing areduction in pressure at the cover engaging member when in receivingposition and for producing a blast of air therethrough when indelivering position.

References Cited in the file of this patent UNITED STATES PATENTS CarperDec. 8, 1914 Bergmann Nov. 5, 1929 Harder July 18, 1933 Young Dec. 27,1938 Le Frank Aug. 8, 1944 Malhiot May 4, 1948 Cloud Mar. 25, 1952Marshall Aug. 18, 1953 Negoro May 1, 1956 Anderson Sept. 2, 1958

